Obsessive compulsive symptoms in bipolar disorder patients: a comorbid disorder or a subtype of bipolar disorder?

Over the last decade increasing attention has been focused on individuals that simultaneously meet the criteria of two or more mental disorders. One of these comorbid conditions, comorbid bipolar disorder and obsessive compulsive disorder, is relatively common among patients with a primary diagnosis of bipolar disorder. But there is little research about the diagnosis and treatment of this comorbid condition, particularly in China. The available studies are primarily cross-sectional studies with small samples, so they are of limited use in understanding the etiology and course of this combined condition. A review of the limited literature suggests that this is a relatively severe, refractory subtype of bipolar disorder that only occasionally merits being considered a comorbid disorder. Larger prospective studies are needed to clarify the etiology, prognosis, and appropriate treatment for this comorbid condition.

The Forum by Peng and Jiang[1] highlights the lack of literature about comorbid bipolar disorder and obsessive compulsive (OCD) disorder. To provide a preliminary summary of the available English-language literature, a search of PubMed using three relevant keywords (‘bipolar disorder’, ‘obsessive compulsive disorder’, and ‘comorbidity’) was conducted in July 2015. Only a few of the 176 papers retrieved by this search were directly related to the topic of interest: most of the relevant papers described the incidence and clinical features of comorbid bipolar disorder and OCD in relatively small samples of patients; some discussed the etiology and treatment of the comorbid condition; and a few reported on prospective, multi-center studies with relatively large samples.

Bipolar-OCD comorbidity was first reported in a 1995 study from Germany[2] which found that more than half of all patients with bipolar disorder had experienced other mental disorders, including OCD, during the course of the bipolar disorder. The study reported that the prevalence of comorbid OCD was higher in patients with unipolar depression than among patients with bipolar disorder. A subsequent systematic review[3] of 64 relevant articles in 2014 reported that from 11 to 21% of persons with bipolar disorder experience comorbid OCD at some time during the course of their bipolar disorder.

Most reports indicate that comorbid OCD exacerbates the symptoms of bipolar disorder and makes the diagnosis and treatment of bipolar disorder more difficult. Compared to OCD patients and bipolar disorder patients without other comorbid conditions, bipolar patients with comorbid OCD have: a) higher rates of obsessive ideas about sex and religion and lower rates of ritual checking;[4] b) higher rates of substance abuse (including use of alcohol, sedatives, caffeine, etc.);[5,6] more episodes of depression, higher rates of suicide, and more frequent admissions to hospitals;[7] and d) more chronic episodes and residual symptoms.[8,9] There were no differences between bipolar patients with and without comorbid OCD in age, gender, education, marital status, age of onset of bipolar disorder, personality, prevalence of psychotic symptoms or rapid cycling, history of suicide attempts, the type of initial bipolar episode (i.e., depressed or manic), and the type of episode that was most prevalent throughout the course of bipolar disorder.[9]

The systematic review by Amerio and colleagues[3] found that compared to bipolar patients without comorbid OCD, patients with bipolar disorder with comorbid OCD were more likely to experience OCD symptoms during an affective disorder episode (75% v. 3%), had a higher mean (sd) number of depressive episodes (8.9 [4.2] v. 4.1 [2.7] episodes), and were more likely to experience an antidepressant-induced manic episode (39% v. 9%). They also found that among patients with comorbid bipolar disorder and OCD, OCD symptoms were more like to occur during depressive episodes than manic episodes (78% v. 64%). Based on their findings, these authors argue that the obsessive-compulsive symptoms observed in these patients were secondary to bipolar disorder, not a co-occurring independent disorder.[3] Following this logic, I recommend that the occurrence of obsessivecompulsive symptoms during the depressive (or manic) episodes of a bipolar disorder should not be sufficient to merit a diagnosis of comorbid bipolar disorder and OCD; this comorbid diagnosis should be restricted to situations in which a patient with bipolar disorder also meets the full OCD symptomatic and duration criteria when the patient is not experiencing a depressive or manic episode.

There are only a few articles about the possible etiology of bipolar-OCD comorbidity. A long-term family study based on a multi-generational dataset[10] (cases registered from January 1969 to 2009 included 19, 814 with OCD, 58, 336 with schizophrenia, 48, 180 with bipolar disorders, and 14, 904 with schizoaffective disorder) found familial associations among individuals with bipolar disorder, OCD, and schizophrenia spectrum disorders. There are also few reports about the long-term prognosis of comorbid bipolar disorder and OCD. One study[11] that followed 20 patients with bipolar disorder without comorbid disorders and 20 patients with comorbid bipolar disorder and OCD for 4 years found no significant differences in the long-term outcomes between the two groups.

The treatment of bipolar-OCD comorbidity is difficult because the use of antidepressants to treat obsessive compulsive disorder may induce manic episodes. The existing literature about the treatment is primarily composed of case reports, retrospective cross-sectional studies, and a few treatment studies with small samples. A recent systematic review that combined the results of four treatment studies[12] found that 42% of patients with comorbid bipolar disorder and OCD were simultaneously treated with multiple mood stabilizers and another 10% needed combined treatment with mood stabilizers and anti-psychotic medications. One of the four studies reported that the combined use of antidepressants and mood stabilizers was effective and another study reported that some patients benefitted from the combined use of mood stabilizers and psychological therapy.[11] Based on currently available information, I recommend that patients with comorbid bipolar disorder and OCD be initially treated with mood stabilizers; if mono-therapy with mood stabilizers is ineffective, adjunctive treatment with selective serotonin reuptake inhibitor antidepressants (which are less likely to induce mania) should be considered. In my opinion, the basic treatment for bipolar-OCD is mood stabilizers and could be combined with antidepressants if the patients do not respond to the single treatment (ineffective).

Despite ongoing debates about the etiology, diagnosis, and treatment of comorbid bipolar disorder and OCD, the clinicians who regularly treat bipolar patients need more high-quality, evidence-based information to improve their identification and management of this relatively severe and refractory subgroup of bipolar patients. Well-designed prospective studies with relatively large samples that are specifically focused on this important subgroup of bipolar disorder patients are needed.